My Windows Security notifies me each boot up that my Windows Defender is not running

manofsteelprime2025 0 Reputation points
2026-09-16T02:33:16.3733333+00:00

Almost every boot-up windows notifies me that Windows Defender Antivirus is not running. But when I check, it is up and running. What is causing this false notification?

Microsoft Security | Microsoft Defender | Other
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  1. AI answer

    2026-09-16T02:33:27.8566667+00:00

    This is a confirmed Microsoft Defender Antivirus issue in recent Defender updates.

    After installing the latest updates for Microsoft Defender Antivirus, Windows can show notifications saying "Microsoft Defender Antivirus is turned off" even though Defender is actually functioning correctly and all settings show it as active. These notifications can appear at startup and intermittently afterward, and they can persist even if notification settings are turned off.

    The issue can occur on any version of Windows or Windows Server running Microsoft Defender Antivirus with the latest Defender updates.

    Microsoft’s stated next step is a fix in a future Microsoft Defender Antivirus update.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. manofsteelprime2025 0 Reputation points
    2026-09-16T02:35:48.9133333+00:00

    Accepted. Then I will wait for the next update to solve this problem.

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  3. ApexNáV 360 Reputation points
    2026-09-16T02:39:11.44+00:00

    Don’t worry. This is a known Microsoft Defender notification bug, and it does not mean that your antivirus is actually disabled.. you can check below Microsoft discussion where users discussed about same notification bug:

    https://learn.microsoft.com/en-ca/answers/questions/5997582/notifications-about-defender-on-start-up

    It will likely get fix in upcomming updates.

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  4. JuliaMarvin 22,815 Reputation points Volunteer Moderator
    2026-09-19T06:21:49.37+00:00

    "This issue was resolved in the Microsoft Defender Antivirus update (version 4.18.26080.4), released on September 17, 2026."

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